1. Field
The present disclosure relates to a frame type dump deck for a dump truck, and more particularly, to a frame type dump deck for a dump truck in which an eye end cylinder is mounted on the frame type dump deck so that cost and weight of the frame type dump deck for the dump truck may be reduced.
2. Background
In general, large dump trucks transport a construction material, such as sand or gravel. A large dump truck consists of a combination of a deck on which a baggage is loaded, and a cylinder that lifts the deck. The deck is classified into a floor type deck and a frame type deck depending on the existence of a reinforcement material on a bottom surface of the deck. The cylinder in this case is determined according to each deck type.
The deck on which a construction material, such as sand or gravel, is loaded, is usually manufactured to have sufficient stiffness. In order to easily load and unload the construction material loaded on the deck, the deck is installed to rotate in a backward direction relative to the dump truck and to ascend.
A loading bay, such as a combination of a floor type deck 100 and an eye end cylinder 110 or a combination of a frame type deck 120 and an outer cover cylinder 130, as illustrated in FIG. 1, is mainly used.
Here, the top of the eye end cylinder 110 is connected to a cylinder hinge of the floor type deck 100, and the bottom of the eye end cylinder 110 is connected to a sub frame.
A lower-side bracket of the outer cover cylinder 130 is connected to a lower pocket face of the frame type deck 120, and the bottom of the outer cover cylinder 130 is connected to a sub frame.
The combination of the floor type deck 100 and the eye end cylinder 110 has a simple structure, is light-weight and is cheap. However, due to weak torsional stiffness, when the loading bay is lifted in an inclined place, the loading bay may be turned over and thus, reinforcement of the deck is required.
The combination of the frame type deck 120 and the outer cover cylinder 130 has large torsional stiffness and high adjustment stability, and any special reinforcement of the deck is not required. However, it has a complicated structure, is heavy and is expensive.
For these reasons, dump trucks made in Korea usually use the combination of the floor type deck and the eye end cylinder, and dump trucks made in countries other than Korea usually use the combination of the frame type deck and the outer cover cylinder.
For example, various types of loading bays are disclosed in U.S. Pat. No. 7,357,457, Korean Patent Laid-open Publication No. 2007-0045079, Japanese Patent Laid-open Publication No. 2007-331677, and Japanese Patent Laid-open Publication No. 06-191341.
FIGS. 2 and 3 are perspective views of a pocket top reinforcement structure of a loading bay including a combination of a floor type deck and an eye end cylinder according to the related art.
As illustrated in FIG. 2, a cylinder hinge 120 is mounted on the top of a pocket 110 disposed on a deck 100, and an outside reinforcement material 130 is deposited around the top of the pocket 110 to which the cylinder hinge 120 belongs.
In general, the top of the pocket 110 is a stiffness discontinuous part and has a high probability of damage. When the cylinder hinge 120 is mounted on the top of the pocket 110, a car torsion phenomenon occurs, and a large peripheral stress occurs during a deck lifting operation so that there is a high probability of damage of peripheral parts of the cylinder hinge 120.
As illustrated in FIG. 3, in order to prevent damage of a portion of the pocket 110 on which the cylinder hinge 120 is mounted, the portion is padded with 10 additional inside reinforcement materials 140-1 to 140-10.
A board that is used in the dump truck is made of ultra-high tensile steel having a yield strength of 1200 MPa or more, and most cracks occur in a welding portion (the yield strength of the welding portion is 500 MPa).
Thus, as the number of welding portions increases, the higher the probability of fatigue damage is.
That is, the durability of a reinforcement material for improving stiffness is lowered
The number of reinforcement patches is large, and the size of a reinforcement member is small, and welding of the reinforcement member is difficult. Thus, there is a disadvantage in production.
FIG. 4 is a perspective view and a cross-sectional view of a pocket bottom reinforcement structure of a loading bay including a combination of a floor type deck and an eye end cylinder according to the related art.
As illustrated in FIG. 4, in the pocket bottom reinforcement structure, a reinforcement member 160 is attached to a circumference of a connection part between a pocket 110 and a floor 150.
In the reinforcement structure, a corner of the reinforcement member 160 serves as a lever hinge so that a stress concentration phenomenon occurs. Thus, bending deformation in which a connection part of a bottom of the reinforcement member 160 of the floor 150 is bent to a downward direction, occurs. As a result, when all loads are concentrated on the floor 150, bending deformation of the floor 150 occurs.